BIOS is stored in a chip on your PC's motherboard not on your hard drive. If you attempt to update the BIOS and it fails then you will not be able to boot your PC. That includes booting TI from the rescue CD as you cannot bypass BIOS in any way. It is fundamental to the correct operation of your motherboard. TI backs up the contents of your disks, including the operating system but is not able to recover a damaged BIOS. That's why your motherboard manufacturer will always warn against flashing BIOS unless it is absolutely necessary to fix a fault. A damaged BIOS renders a motherboard totally inoperable. Some motherboard manufacturers provide a means of recovering a damaged BIOS but you will have to refer to documentation provided by your motherboard manufacturer to ascertain what procedure to follow.